I'm not sure that's completely true at least for me. There's multiple instances of new technology I first tried as an adult that seemed amazing, I didn't get online till my mid twenties and that was an amazing experience. Switching from my 8MHz Atari ST to an 800MHz PC happened at the same time and suddenly getting access to all these new games and new software was magical, I marvelled at all the little graphical and audio details games suddenly had. I got my first camcorder and digital cameras as an adult and thought they were great.

The magic started to wear off later when technology started feeling hostile. Instead of me being in charge, my technology started doing things against my wishes and I had no power to stop it. There's been this increasing sense of technology constantly pushing and clawing at my boundaries, trying to spy on my and report back from me unless I check a dozen options and even then it may not be enough. Technology updating itself when its inconvenient, or breaking itself, or installing stuff I didn't ask for, want or consent to.

There's also the fact that this creepy boundary pushing technology is feeling more and more mandatory and a built in part of society, so its becoming harder to avoid and the sense that 90% of people have just shrugged given up.

But even now in my 40s I occasionally find a gadget or bit of software that seems magical, so I don't think for me its an age thing.

I'm sure lots of people disagree and have a very different experience, but for me that's a big part of why technology has lost its magic.